Stunning Images of the Curiosity Rover’s Martian Playground

Geologists believe that the highest layers in this image (near the bottom of the scene) are an exotic type of geological phenomenon known as an inverted river channel. When sedimentary layers are bound together, the thinking goes, they form a strong, coherent layer. Later, erosive processes sweep surrounding sediment away, leaving the ancient river channel and its deposits as a topographic high.

Image: NASA/JPL/University of Arizona

Well-defined layers of sedimentary rocks are seen in this image -- the stuff of a Mars geologist's dreams. The mechanism of formation is unknown, but the units could correspond to lake, river, or wind-blown deposits of dust of volcanic ash.

Image: NASA/JPL/University of Arizona

The dark patches at the top of this frame show the southeastern edge of Mt. Sharp; the floor of Gale Crater occupies the remainder of the image. Small hills dotted with rocks and debris populate Mt. Sharp’s margin, implying that the constituent rock is easily eroded by wind scouring the hillside.

Polygonal terrain is evident along the lower and right sides of the image; many scientists believe these patterns are caused by the contraction of sediment blocks due to water loss or cooling, much like mud cracks in the desert. Polygons are abundant at Mars’ higher latitudes and were the focus of the Phoenix Mars Lander mission.

Image: NASA/JPL/University of Arizona

This image shows the edge of a distinctive type of light-toned layered deposits that are found in many equatorial craters, including Gale Crater. At the top of the image, there is a heavily cratered flat surface, which is cut by a large canyon where dark sand has collected to form dunes.

Ridges and dune crests are generally oriented along an upper left to lower right axis, indicating the dominant directions of the rock-eroding wind.

Image: NASA/JPL/University of Arizona

This image shows a young crater inside Gale with sharp, recently formed ridges. Of course, young is a relative term for a geologist; this crater may have formed tens of thousands of years ago.

Image: NASA/JPL/University of Arizona

The Curiosity rover is about to finally begin its mission on Mars, after years – decades, depending on who’s telling the story – of instrument development and mission planning. One key aspect of that planning was the selection of the mission’s landing site. The target is Gale Crater, a 154-kilometer diameter impact crater that formed between about 3.5 and 3.8 billion years ago.

Gale Crater’s starring role came about after several occasionally heated debates that sought to identify the most scientifically valuable but logistically feasible landing site possible. Scientists were enamored with the crater’s central mound – known as Mt. Sharp – which exhibits a phenomenal series of layered rock deposits. Engineers were initially skeptical: previous missions would have deemed the site too risky, but enhanced navigational procedures gave MSL the green light.

Ashwin Vasaveda, the mission’s Deputy Project Scientist, explained the benefits in a presentation at the Mars Society’s annual convention in Pasadena on Saturday. “We’re landing more accurately than any previous mission, which allows us to put our ellipse next to something that is far too dangerous to actually land on,” he said, referring to Mt. Sharp.

The mound’s layers are best seen with the Mars Reconnaissance Orbiter’s HiRISE camera – the highest resolution camera ever flown around the Red Planet. In the vernacular of sedimentary geology, different layers result from different environmental conditions, so the mineralogically distinct deposits mean that Curiosity should see clues of many past martian environments.

The images that follow show some of HiRISE’s greatest hits from Gale Crater, a preview of geological features that Curiosity may soon get to know in intimate detail.

Above:

In the image above, several geological processes have been at work, from wind-formed dunes to impact craters to potential river erosion. Many of the rock units shown here displayed spectroscopic signatures of sulfates and clays – the types of rocks that drew scientists to Gale in the first place due to their association with water.

Image: NASA/JPL/University of Arizona

A quick note about the color enhancement in the HiRISE images. From the HiRISE team:

“We can make some generalizations to better understand what the stretched color images are showing. Dust (or indurated dust) is generally the reddest material present and looks reddish in the RGB color and yellow in the IRB color. Coarser-grained materials (sand and rocks) are generally bluer (or sometimes purplish in IRB color) but also relatively dark, except where coated by dust. Frost and ice are also relatively blue, but bright, and often concentrated at the poles or on pole-facing slopes. Some bedrock is also relatively bright and blue, but not as much as frost or ice, and it has distinctive morphologies.”